#include <DB/Dictionaries/ODBCBlockInputStream.h>

#include <DB/Columns/ColumnsNumber.h>
#include <DB/Columns/ColumnString.h>

#include <ext/range.hpp>
#include <vector>


namespace DB
{

namespace ErrorCodes
{
	extern const int NUMBER_OF_COLUMNS_DOESNT_MATCH;
}


ODBCBlockInputStream::ODBCBlockInputStream(
	Poco::Data::Session && session, const std::string & query_str, const Block & sample_block,
	const size_t max_block_size)
	:
	session{session},
	statement{(this->session << query_str, Poco::Data::Keywords::now)},
	result{statement},
	iterator{result.begin()},
	max_block_size{max_block_size}
{
	if (sample_block.columns() != result.columnCount())
		throw Exception{
			"RecordSet contains " + toString(result.columnCount()) + " columns while " +
				toString(sample_block.columns()) + " expected",
			ErrorCodes::NUMBER_OF_COLUMNS_DOESNT_MATCH};

	description.init(sample_block);
}


String ODBCBlockInputStream::getID() const
{
	return "ODBC(" + statement.toString() + ")";
}


namespace
{
	using ValueType = ExternalResultDescription::ValueType;

	static void insertValue(IColumn * const column, const ValueType type, const Poco::Dynamic::Var & value)
	{
		switch (type)
		{
			case ValueType::UInt8: static_cast<ColumnUInt8 *>(column)->insert(value.convert<UInt64>()); break;
			case ValueType::UInt16: static_cast<ColumnUInt16 *>(column)->insert(value.convert<UInt64>()); break;
			case ValueType::UInt32: static_cast<ColumnUInt32 *>(column)->insert(value.convert<UInt64>()); break;
			case ValueType::UInt64: static_cast<ColumnUInt64 *>(column)->insert(value.convert<UInt64>()); break;
			case ValueType::Int8: static_cast<ColumnInt8 *>(column)->insert(value.convert<Int64>()); break;
			case ValueType::Int16: static_cast<ColumnInt16 *>(column)->insert(value.convert<Int64>()); break;
			case ValueType::Int32: static_cast<ColumnInt32 *>(column)->insert(value.convert<Int64>()); break;
			case ValueType::Int64: static_cast<ColumnInt64 *>(column)->insert(value.convert<Int64>()); break;
			case ValueType::Float32: static_cast<ColumnFloat32 *>(column)->insert(value.convert<Float64>()); break;
			case ValueType::Float64: static_cast<ColumnFloat64 *>(column)->insert(value.convert<Float64>()); break;
			case ValueType::String: static_cast<ColumnString *>(column)->insert(value.convert<String>()); break;
			case ValueType::Date: static_cast<ColumnUInt16 *>(column)->insert(UInt16{LocalDate{value.convert<String>()}.getDayNum()}); break;
			case ValueType::DateTime: static_cast<ColumnUInt32 *>(column)->insert(time_t{LocalDateTime{value.convert<String>()}}); break;
		}
	}
}


Block ODBCBlockInputStream::readImpl()
{
	if (iterator == result.end())
		return {};

	auto block = description.sample_block.cloneEmpty();

	/// cache pointers returned by the calls to getByPosition
	std::vector<IColumn *> columns(block.columns());
	for (const auto i : ext::range(0, columns.size()))
		columns[i] = block.safeGetByPosition(i).column.get();

	size_t num_rows = 0;
	while (iterator != result.end())
	{
		Poco::Data::Row & row = *iterator;

		for (const auto idx : ext::range(0, row.fieldCount()))
		{
			const Poco::Dynamic::Var & value = row[idx];

			if (!value.isEmpty())
				insertValue(columns[idx], description.types[idx], value);
			else
				insertDefaultValue(columns[idx], *description.sample_columns[idx]);
		}

		++num_rows;
		if (num_rows == max_block_size)
			break;

		++iterator;
	}

	return block;
}

}
